A vehicle air bag assembly functions to protect a vehicle occupant during a crash or collision. At the onset of a collision, the air bag assembly deploys and inflates an air bag in front of a vehicle occupant who is being pitched forward by the force of the collision. The air bag absorbs the occupant's energy and retards forward movement of the occupant, to prevent the occupant from striking a rigid part of the vehicle. On the driver side of a vehicle, an air bag assembly is commonly incorporated into the vehicle steering wheel. On the passenger side of the vehicle, the air bag assembly is commonly incorporated into the vehicle instrument panel.
Typically, a vehicle air bag assembly includes a storage device for the air bag, and a fluid source which is actuated at the onset of collision for directing fluid into the air bag. The storage device includes a closure interposed between the air bag and the occupant compartment. When the fluid source directs fluid into the air bag, the air bag begins to inflate, and applies a force to the closure. The closure defines part of a separable connection which opens in response to that force to create a deployment opening through which the air bag can be deployed into the occupant compartment and fully inflated in front of a vehicle occupant.
Several different techniques are presently known for forming a separable connection which opens to create a deployment opening for an air bag. One known technique is to form the closure with weakened portions which break to create the deployment opening (see, e.g., U.S. Pat. No. 4,938,503). Another known technique is to form the closure with portions which are connected together by fused or welded seams which break to form the deployment opening (see e.g. U.S. Pat. Nos. 3,640,546 and 4,400,010). Still another known technique is to connect edge portions of the closure to other parts of the storage device by joints or tear strips which break to enable the closure to move relative to the other parts of the storage device to form the deployment opening (see e.g. U.S. Pat. No. 3,514,124). Yet another known technique is to press opposed portions of the closure against each other in such a way that the portions slide relative to each other to form the deployment opening (see e.g. U.S. Pat. No. 3,904,222).
Regardless of how the separable connection is formed, it should be designed to respond in a predictable manner to the force applied to the closure by an expanding air bag. Also, applicants believe the separable connection should be designed to enable the closure to be efficiently formed and incorporated into an air bag assembly, preferably by mass production techniques.
The present invention relates to a new and useful separable connection for an air bag assembly. The separable connection is designed to respond in a predictable manner to the pressure applied to the closure by an expanding air bag to form a deployment opening for the air bag. Moreover, the separable connection is designed to enable the closure to be efficiently formed and incorporated into an air bag assembly, preferably by mass production techniques.
The type of separable connection provided according to the invention is believed to be unusual for an air bag assembly. The separable connection includes connection surfaces which are connected to each other by a device which provides relatively high resistance to separation of the connection surfaces in a shear direction. At the same time, the separable connection is designed to enable the connection surfaces to separate primarily by movement relative to each other in the shear direction. ("Shear direction" in this context corresponds to a direction which is generally parallel to the connection surfaces.) Indeed, certain preferred structures for a separable connection according to the invention are particularly unusual because they use connection devices with a high resistance to separation in shear which has been specifically utilized in other contexts to create essentially permanent connections (see, e.g., Perina, U.S. Pat. No. 4,271,566). Nevertheless, applicants have incorporated such structures into separable connections designed to separate by movement primarily in a shear direction, but with the consistency and predictability required for an air bag assembly. Also, applicants have designed the separable connections to be particularly simple and efficient to incorporate into an air bag assembly by mass production techniques.
An air bag assembly according to the present invention comprises an inflatable air bag, a closure interposed between the air bag and an occupant compartment, and a fluid source for supplying fluid to the air bag to cause the air bag to inflate towards the occupant compartment. The air bag is positioned to apply a deployment force to the closure upon receiving fluid from the source. The closure defines at least part of a separable connection which opens in response to the deployment force so as to create a deployment opening through which the air bag can be deployed into the occupant compartment and inflated adjacent to a vehicle occupant. The separable connection is at least partially defined by a first connection surface, a second connection surface positioned adjacent to the first connection surface, and a connection device connecting the first and second connection surfaces together. The deployment opening is formed by movement of the first and second connection surfaces relative to each other in a shear direction that is generally parallel to the first and second connection surfaces.
In one form of an air bag assembly according to the present invention, the separable connection is formed between portions of the closure which separate from each other by movement in the shear direction in response to the deployment force.
In another form of an air bag assembly according to the invention, the separable connection is formed between an edge portion of the closure and a receptacle which forms a storage device for the air bag. When the air bag applies a deployment force to the closure, the edge portion of the closure separates from the receptacle to create the deployment opening for the air bag.
Two preferred types of devices for interconnecting the connection surfaces of a separable connection according to the present invention are: (i) "hook-and-loop" fasteners, such as fasteners sold under the trademark VELCRO.sup.TM, and (ii) "dual-lock" fasteners which are marketed by The Automotive Specialties Division of Minnesota Mining & Manufacturing Co. under the name "Dual Lock Fastening Systems" (hereinafter referred to as "Dual Lock"). Both types of fasteners enable the connection surfaces to be connected to each other simply and efficiently, but provide a high resistance to separation of the connection surfaces in a shear direction.
According to the present invention, the hook-and-loop and/or "Dual-Lock" fasteners are incorporated into a separable connection in such a manner that the separable connection can open only by movement of the connection surfaces in a shear direction. Applicants believe such fasteners are particularly attractive for an air bag assembly because they allow the connection surfaces to be connected to each other simply and efficiently, and thus enable the closure to be efficiently formed and incorporated into an air bag assembly by mass production techniques. Additionally, such fasteners enable the separable connection to be completed prior to, during, or after, the installation of the air bag assembly into a vehicle. Still further, such fasteners can be conveniently separated by peeling the connection surfaces relative to each other, thereby enabling the separable connection to be selectively opened (e.g. for inspection, shipping, removal of loose parts, etc.) and then selectively closed to re-establish a complete air bag assembly.
Further features of the present invention will become apparent from the following detailed description and the annexed drawings.